Assessment of the influence of an enzymal preparation - a complex of glucoamylase and xylanase from Aspergillus awamori Xyl T-15 on the intestinal microbiom and immunological indicators of rats

Abstract

The requirements for the safety of food products obtained by microbial synthesis are including as obligation for to conduct toxicological studies - the study of various biochemical and immunological markers of toxic effects. The necessity of these studies is explained by a possible change in the structure of food ingredients produced by a microbial cell and, consequently, a change in their biological properties, as well as the possible presence of living forms and/or DNA of producer strains or of their toxic metabolites in these ingredients. At the same time, it is well known that the nutrient composition of foods has a significant impact on the composition and properties of microorganisms that make up the gut microbiome, which, in turn, determines the immune status. The purpose of the research was to justify the analyses of gut microbiocenosis composition for inclusion in the protocol of safety investigation of foods obtained by microbial synthesis [on the example of an enzyme preparation (EP) - a complex of glucoamylase and xylanase from a genetically modified strain of Aspergillus awamori Xyl T-15]. Material and methods. In experimental studies carried out for 80 days, Wistar rats (males and females) were used. The study of the effect of EP (a complex of glucoamylase and xylanase from a genetically modified Aspergillus awamori Xyl T-15 strain) in dozes 10, 100 and 1000 mg/kg body mass on the cecum microbiome and the immune status (content of cytokines and chemokines: IL-1a, IL-4, IL-6, IL-10, IL-17A, INF-γ, TNF-α, MCP-1, MIP-1a and Regulated on Activation Normal T-cell Expressed and Secreted - RANTES) was carried out. Results. It has been shown that EP - a complex of glucoamylase and xylanase from A. awamori Xyl T-15 at doses of 100 mg/kg or more causes mild disturbances in the composition of gut microbiocenosis. At the same time, these disorders have a significant immunomodulat ory and immunotoxic effect on the body, which manifests itself in a dose-dependent change in the profile of pro-inflammatory cytokines and chemokines in blood and spleen. The adverse effect of EP on the body is probably due to the formation of metabolites that are not formed during usual digestive processes in the gastrointestinal tract. The minimum effective dose (LOAEL) of EP was 100 mg/kg body weight In accordance with established requirements, the activity of the EP should not appear in ready-to-use food. Subject to this requirement, amount of EP entering the body cannot exceed the established LOAEL level. Therefore, a complex of glucoamylase and xylanase can be used in food industry, subject to the establishment of regulations «for technological purposes» for A. awamori Xyl T-15 strain. Conclusion. The data obtained on the relationship between the state of the microbiome and the immune status upon the introduction of EP indicate the need to include indicators of the state of gut microbiocenosis in the test protocol of safety.